Polymers of ethylene are important items of commerce, and these polymers are used in a myriad of ways, from low molecular weight polyethylene (PE) being used as a lubricant and in waxes, to higher molecular weight grades being used for fiber, films, molding resins, etc. In most cases, ethylene is polymerized using a catalyst, often a transition metal compound or complex. These catalysts vary in cost per unit weight of PE produced, the structure of the polymer produced, the possible need to remove the catalyst from the PE, the toxicity of the catalyst, etc. Due to the commercial importance of polymerizing ethylene, new polymerization catalysts are constantly being sought.
P. Braunstein, et al., J. Chem. Soc., Dalton Trans., 1996, p. 3571-3574 report the use of nickel complexes having certain phosphorous-nitrogen ligands as oligomerization catalysts for ethylene. Sulfonamides are not mentioned.
European Patent Application 454,231 discloses certain types of neutral phosphorous ligands in nickel complexes as being useful in olefin polymerizations. Ligands containing sulfonamides are not disclosed.